linux/mm
Mel Gorman d0164adc89 mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd
__GFP_WAIT has been used to identify atomic context in callers that hold
spinlocks or are in interrupts.  They are expected to be high priority and
have access one of two watermarks lower than "min" which can be referred
to as the "atomic reserve".  __GFP_HIGH users get access to the first
lower watermark and can be called the "high priority reserve".

Over time, callers had a requirement to not block when fallback options
were available.  Some have abused __GFP_WAIT leading to a situation where
an optimisitic allocation with a fallback option can access atomic
reserves.

This patch uses __GFP_ATOMIC to identify callers that are truely atomic,
cannot sleep and have no alternative.  High priority users continue to use
__GFP_HIGH.  __GFP_DIRECT_RECLAIM identifies callers that can sleep and
are willing to enter direct reclaim.  __GFP_KSWAPD_RECLAIM to identify
callers that want to wake kswapd for background reclaim.  __GFP_WAIT is
redefined as a caller that is willing to enter direct reclaim and wake
kswapd for background reclaim.

This patch then converts a number of sites

o __GFP_ATOMIC is used by callers that are high priority and have memory
  pools for those requests. GFP_ATOMIC uses this flag.

o Callers that have a limited mempool to guarantee forward progress clear
  __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall
  into this category where kswapd will still be woken but atomic reserves
  are not used as there is a one-entry mempool to guarantee progress.

o Callers that are checking if they are non-blocking should use the
  helper gfpflags_allow_blocking() where possible. This is because
  checking for __GFP_WAIT as was done historically now can trigger false
  positives. Some exceptions like dm-crypt.c exist where the code intent
  is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to
  flag manipulations.

o Callers that built their own GFP flags instead of starting with GFP_KERNEL
  and friends now also need to specify __GFP_KSWAPD_RECLAIM.

The first key hazard to watch out for is callers that removed __GFP_WAIT
and was depending on access to atomic reserves for inconspicuous reasons.
In some cases it may be appropriate for them to use __GFP_HIGH.

The second key hazard is callers that assembled their own combination of
GFP flags instead of starting with something like GFP_KERNEL.  They may
now wish to specify __GFP_KSWAPD_RECLAIM.  It's almost certainly harmless
if it's missed in most cases as other activity will wake kswapd.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-06 17:50:42 -08:00
..
kasan kasan: always taint kernel on report 2015-11-05 19:34:48 -08:00
backing-dev.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
balloon_compaction.c mm: page migration trylock newpage at same level as oldpage 2015-11-05 19:34:48 -08:00
bootmem.c bootmem: avoid freeing to bootmem after bootmem is done 2015-09-08 15:35:28 -07:00
cleancache.c cleancache: remove limit on the number of cleancache enabled filesystems 2015-04-14 16:49:03 -07:00
cma_debug.c mm/cma_debug: correct size input to bitmap function 2015-07-17 16:39:54 -07:00
cma.c mm/cma.c: suppress warning 2015-11-05 19:34:48 -08:00
cma.h mm: cma: mark cma_bitmap_maxno() inline in header 2015-08-14 15:56:32 -07:00
compaction.c mm, compaction: distinguish contended status in tracepoints 2015-11-05 19:34:48 -08:00
debug-pagealloc.c mm/debug-pagealloc: make debug-pagealloc boottime configurable 2014-12-13 12:42:48 -08:00
debug.c mm: introduce VM_LOCKONFAULT 2015-11-05 19:34:48 -08:00
dmapool.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
early_ioremap.c mm/early_ioremap: use offset_in_page macro 2015-11-05 19:34:48 -08:00
fadvise.c writeback: implement and use inode_congested() 2015-06-02 08:33:35 -06:00
failslab.c debugfs: Pass bool pointer to debugfs_create_bool() 2015-10-04 11:36:07 +01:00
filemap.c mm: rename mem_cgroup_migrate to mem_cgroup_replace_page 2015-11-05 19:34:48 -08:00
frame_vector.c mm: fix docbook comment for get_vaddr_frames() 2015-11-05 19:34:48 -08:00
frontswap.c frontswap: allow multiple backends 2015-06-24 17:49:45 -07:00
gup.c mm: introduce VM_LOCKONFAULT 2015-11-05 19:34:48 -08:00
highmem.c mm/highmem: make kmap cache coloring aware 2014-08-06 18:01:22 -07:00
huge_memory.c mm: introduce VM_LOCKONFAULT 2015-11-05 19:34:48 -08:00
hugetlb_cgroup.c mm: page_counter: let page_counter_try_charge() return bool 2015-11-05 19:34:48 -08:00
hugetlb.c mm: introduce VM_LOCKONFAULT 2015-11-05 19:34:48 -08:00
hwpoison-inject.c hwpoison: use page_cgroup_ino for filtering by memcg 2015-09-10 13:29:01 -07:00
init-mm.c
internal.h mm, page_alloc: remove unnecessary recalculations for dirty zone balancing 2015-11-06 17:50:42 -08:00
interval_tree.c mm: replace vma->sharead.linear with vma->shared 2015-02-10 14:30:31 -08:00
Kconfig media updates for v4.3-rc1 2015-09-11 16:42:39 -07:00
Kconfig.debug mm/debug_pagealloc: remove obsolete Kconfig options 2015-01-08 15:10:52 -08:00
kmemcheck.c mm/slab_common: move kmem_cache definition to internal header 2014-10-09 22:25:50 -04:00
kmemleak-test.c mm/kmemleak-test.c: use pr_fmt for logging 2014-06-06 16:08:18 -07:00
kmemleak.c mm/kmemleak.c: remove unneeded initialization of object to NULL 2015-11-05 19:34:48 -08:00
ksm.c ksm: unstable_tree_search_insert error checking cleanup 2015-11-05 19:34:48 -08:00
list_lru.c memcg: simplify and inline __mem_cgroup_from_kmem 2015-11-05 19:34:48 -08:00
maccess.c mm/maccess.c: actually return -EFAULT from strncpy_from_unsafe 2015-11-05 19:34:48 -08:00
madvise.c mm: madvise allow remove operation for hugetlbfs 2015-09-08 15:35:28 -07:00
Makefile media updates for v4.3-rc1 2015-09-11 16:42:39 -07:00
memblock.c mm/memblock: make memblock_remove_range() static 2015-11-05 19:34:48 -08:00
memcontrol.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
memory_hotplug.c mm/page_alloc: remove unused parameter in init_currently_empty_zone() 2015-11-05 19:34:48 -08:00
memory-failure.c mm: hwpoison: ratelimit messages from unpoison_memory() 2015-11-05 19:34:48 -08:00
memory.c mm, dax: fix DAX deadlocks 2015-10-16 11:42:28 -07:00
mempolicy.c mm: rename alloc_pages_exact_node() to __alloc_pages_node() 2015-09-08 15:35:28 -07:00
mempool.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
memtest.c memtest: remove unused header files 2015-09-08 15:35:28 -07:00
migrate.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
mincore.c mm/mincore: use offset_in_page macro 2015-11-05 19:34:48 -08:00
mlock.c mm: mlock: add mlock flags to enable VM_LOCKONFAULT usage 2015-11-05 19:34:48 -08:00
mm_init.c mm: meminit: remove mminit_verify_page_links 2015-06-30 19:44:56 -07:00
mmap.c mm: introduce VM_LOCKONFAULT 2015-11-05 19:34:48 -08:00
mmu_context.c sched/mm: call finish_arch_post_lock_switch in idle_task_exit and use_mm 2014-02-21 08:50:17 +01:00
mmu_notifier.c mmu-notifier: add clear_young callback 2015-09-10 13:29:01 -07:00
mmzone.c mm: microoptimize zonelist operations 2015-02-11 17:06:02 -08:00
mprotect.c userfaultfd: teach vma_merge to merge across vma->vm_userfaultfd_ctx 2015-09-04 16:54:41 -07:00
mremap.c mm/mremap: use offset_in_page macro 2015-11-05 19:34:48 -08:00
msync.c mm/msync: use offset_in_page macro 2015-11-05 19:34:48 -08:00
nobootmem.c mm: page_alloc: pass PFN to __free_pages_bootmem 2015-06-30 19:44:55 -07:00
nommu.c mm/nommu.c: drop unlikely inside BUG_ON() 2015-11-05 19:34:48 -08:00
oom_kill.c mm/oom_kill.c: introduce is_sysrq_oom helper 2015-11-06 17:50:42 -08:00
page_alloc.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
page_counter.c mm: page_counter: let page_counter_try_charge() return bool 2015-11-05 19:34:48 -08:00
page_ext.c mm: introduce idle page tracking 2015-09-10 13:29:01 -07:00
page_idle.c mm: introduce idle page tracking 2015-09-10 13:29:01 -07:00
page_io.c fs: use helper bio_add_page() instead of open coding on bi_io_vec 2015-08-13 12:32:00 -06:00
page_isolation.c mm, page_isolation: make set/unset_migratetype_isolate() file-local 2015-09-08 15:35:28 -07:00
page_owner.c mm/page_owner: set correct gfp_mask on page_owner 2015-07-17 16:39:54 -07:00
page-writeback.c writeback: fix incorrect calculation of available memory for memcg domains 2015-10-12 10:31:13 -06:00
pagewalk.c mm/pagewalk.c: prevent positive return value of walk_page_test() from being passed to callers 2015-03-25 16:20:30 -07:00
percpu-km.c percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated 2014-09-02 14:46:05 -04:00
percpu-vm.c percpu: move region iterations out of pcpu_[de]populate_chunk() 2014-09-02 14:46:02 -04:00
percpu.c mm/percpu: use offset_in_page macro 2015-11-05 19:34:48 -08:00
pgtable-generic.c mm,thp: introduce flush_pmd_tlb_range 2015-10-17 17:48:20 +05:30
process_vm_access.c process_vm_access: switch to {compat_,}import_iovec() 2015-04-11 22:27:12 -04:00
quicklist.c
readahead.c mm: use only per-device readahead limit 2015-11-05 19:34:48 -08:00
rmap.c mm: page migration use migration entry for swapcache too 2015-11-05 19:34:48 -08:00
shmem.c tmpfs: avoid a little creat and stat slowdown 2015-11-05 19:34:48 -08:00
slab_common.c mm/slab_common.c: initialize kmem_cache pointer to NULL 2015-11-05 19:34:48 -08:00
slab.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
slab.h memcg: unify slab and other kmem pages charging 2015-11-05 19:34:48 -08:00
slob.c mm: rename alloc_pages_exact_node() to __alloc_pages_node() 2015-09-08 15:35:28 -07:00
slub.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
sparse-vmemmap.c
sparse.c mm: use macros from compiler.h instead of __attribute__((...)) 2014-04-07 16:35:54 -07:00
swap_cgroup.c mm: page_cgroup: rename file to mm/swap_cgroup.c 2014-12-10 17:41:09 -08:00
swap_state.c mm: swap: zswap: maybe_preload & refactoring 2015-09-08 15:35:28 -07:00
swap.c mm: introduce idle page tracking 2015-09-10 13:29:01 -07:00
swapfile.c mm: /proc/pid/smaps:: show proportional swap share of the mapping 2015-09-08 15:35:28 -07:00
truncate.c memcg: add per cgroup dirty page accounting 2015-06-02 08:33:33 -06:00
userfaultfd.c userfaultfd: avoid mmap_sem read recursion in mcopy_atomic 2015-09-04 16:54:41 -07:00
util.c mm/util: use offset_in_page macro 2015-11-05 19:34:48 -08:00
vmacache.c mm/vmacache: inline vmacache_valid_mm() 2015-11-05 19:34:48 -08:00
vmalloc.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
vmpressure.c mm/vmpressure.c: fix race in vmpressure_work_fn() 2014-12-02 17:32:07 -08:00
vmscan.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
vmstat.c mm/vmstat.c: uninline node_page_state() 2015-11-05 19:34:48 -08:00
workingset.c list_lru: add helpers to isolate items 2015-02-12 18:54:10 -08:00
zbud.c mm: zbud: constify the zbud_ops 2015-09-08 15:35:28 -07:00
zpool.c zpool: add zpool_has_pool() 2015-09-10 13:29:01 -07:00
zsmalloc.c mm: zpool: constify the zpool_ops 2015-09-08 15:35:28 -07:00
zswap.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00